An approach to investigate new particle formation in the vertical direction on the basis of high time-resolution measurements at ground level and sea level

He, Meng; Zhu, Yujiao; Evans, Greg J.; Yao, Xiaohong

doi:10.1016/j.atmosenv.2014.12.016

Cited by 16 publications

(14 citation statements)

References 34 publications

(47 reference statements)

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“…However, the percentage contribution of nucleation mode particles to the total number concentration over the NWPO (40%) was twice as large as the marginal seas (20%), implying the important role of nucleation mode particles as a source of atmospheric particles over the NWPO. The observed high percentage of N<30 nm over NWPO was primarily a result of either direct generation in the marine boundary layer or downward transport from high altitude such as free troposphere (Clarke et al, 1998;Kulmala and Kerminen, 2008;Meng et al, 2015;Ueda et al, 5 2016). …”

Section: Particle Number Concentrations and Size Distributions In Prementioning

confidence: 99%

New particle formation in marine atmosphere during seven cruise campaigns

Zhu

Shen

et al. 2018

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Abstract. To study the particle number concentration, size distribution and new particle formation (NPF) events in marine atmosphere, we made measurements during six cruise campaigns over the marginal seas of China in 2011-2016 and one 10 campaign from the marginal seas to the Northwest Pacific Ocean (NWPO) in 2014. We observed relatively frequent NPF events in the atmosphere over the marginal seas of China, i.e., 23 out of 126 observational days with the highest occurrence frequency in fall, followed by spring and summer. 22 out of 23 NPF events were analyzed to be associated with the long-range transport of continental pollutants based on 24-hr air mass back trajectories and the pre-existing particle number concentrations largely exceeding the clean marine background, leaving one much weaker NPF event to be likely induced by oceanic precursors 15 alone and supported by multiple independent evidences. Although the long-range transport signal of continental pollutants can be clearly observed in the remote marine atmosphere over the NWPO, NPF events were observed only in 2 days out of 36 days. The nucleation mode particles (<30 nm), however, accounted for as high as 40%13% of the total particle number concentration during the NWPO cruise campaign, implying that there were many undetected NPF events in the sea-level atmosphere or above. 20To better characterize NPF events, we introduced a term, i.e., the net maximum increase in nucleation mode particles number concentration (NMINP) and correlated it with formation rate of new particles (FR). We found a moderately good linear correlation between NMINP and FR at FR 8 cm -3 s -1 , but there was no correlation at FR >8 cm -3 s -1. The possible mechanisms were argued in terms of roles of different vapor precursors. We also found a ceiling existing for the growth of new particles from 10 nm to larger size in most of NPF events. We thereby introduce a term, i.e., the maximum geometric 25 median diameter of new particles (Dpgmax) and correlate it with the growth rate of new particles (GR). A moderately good linear correlation was also obtained between Dpgmax and GR, and only GR larger than 7.9 nm h -1 can lead to new particles growing with Dpgmax beyond 50 nm. Combining simultaneous measurements of the particle number size distributions and cloud condensation nuclei (CCN) at different super saturations (SS), we indeed observed a clear increase in CCN when the Dpg of new particles exceeded 50 nm at SS=0.4%. However, it was not the case for SS=0.2%. Consistent with previous studies in 30 continental atmosphere, our results implied that 50 nm can be used as the threshold for new particles to be activated as CCN in the marine atmosphere. Moreover, the κ decreased from 0.4 to 0.1 during the growth period of new particles, implying that Atmos. Chem. Phys. Discuss., https://doi

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Section: Particle Number Concentrations and Size Distributions In Prementioning

confidence: 99%

New particle formation in marine atmosphere during seven cruise campaigns

Zhu

Shen

et al. 2018

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“…During the whole campaign over the NWPO, only two new particle formation (NPF) events were observed on DOY 98 and DOY 103. Unlike previous studies in the marginal seas of China (Liu et al, 2014;Meng et al, 2015) and in the south subtropical Pacific (Ueda et al, 2016), the events in this study lasted for a short time. The newly formed particles apparently grew to a size smaller than 20 nm during the events.…”

Section: New Particle Formation Events In the Nwpomentioning

confidence: 77%

Large increases in Ncn and Nccn together with a nucleation-modeparticle pool over the northwestern Pacific Ocean in the spring of 2014

Wang

Shen

et al. 2019

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Abstract. The updated concentrations of atmospheric particles (Ncn) and the concentrations of cloud condensation nuclei (Nccn) over the northwestern Pacific Ocean (NWPO) were important to accurately evaluate the influence of aerosol outflow from the Asian continent on the climate by considering rapid changes in emissions of air pollutants therein. However, field observations were scarce in the last two decades. We conducted a cruise campaign over the NWPO to simultaneously measure Ncn, Nccn and the size distribution of aerosol particles from DOY 81 to DOY 108 of 2014. The mean values of Nccn at supersaturation (SS) of 0.2&#8201;% and 0.4&#8201;% were 0.68&#8201;&#177;&#8201;0.38&#215;103&#8201;cm&#8722;3 and 1.1&#8201;&#177;&#8201;0.67&#215;103&#8201;cm&#8722;3, respectively, with an average for Ncn of 2.8&#8201;&#177;&#8201;1.0&#215;103&#8201;cm&#8722;3 during the cruise over the NWPO, which were all approximately one order of magnitude larger than spring observations from two decades ago in the atmosphere of remote marine areas. The higher values, against the marine natural background reported in the literature, implied an overwhelming contribution from continental inputs. The calculated CCN activity ratios were 0.30&#8201;&#177;&#8201;0.11 and 0.46&#8201;&#177;&#8201;0.19 at SS of 0.2&#8201;% and 0.4&#8201;%, respectively, which were almost the same as those of upwind semi-urban sites. High Nccn and CCN activities were observed from DOY 98 to 102, when the oceanic zone received even stronger continental inputs. During the whole cruise period with the exclusion of biomass burning and dust aerosols, a good correlation between Nccn at 0.4&#8201;% SS and the number concentrations of >&#8201;60&#8201;nm particles (N>&#8201;60&#8201;nm), with the slope of 0.98 and R2&#8201;=&#8201;0.94, was obtained, and the corresponding effective hygroscopicity parameter (k) was estimated as 0.40. The bimodal size distribution pattern of the particle number concentration was generally observed during the entire campaign when the N>&#8201;90&#8201;nm varied largely. However, the N<&#8201;30&#8201;nm, accounting for approximately 1&#8201;/&#8201;3 of the total number concentration, varied narrowly, and two NPF events associated with vertical transport were observed, implying a pool of nucleation mode atmospheric particles aloft. Biomass burning (BB) and dust events were observed over the NWPO, but the contributions of BB and dust aerosols to Ncn and Nccn were minor (i.e., 10&#8201;% or less) on the monthly time scale.

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“…S6a, b). In addition, the spikes of PNSDs during this NPF event indicated the vertical transport of atmospheric particles (Meng et al, 2015). We infer that this NPF event seemingly occurred in the free troposphere, and a large decrease in the entrainment from the free troposphere to the boundary layer may have led to the disappearance of the new particle signal.…”

Section: Question 2: Did the Contribution Of Npf Events To Ccn Populamentioning

confidence: 77%

Increased new particle yields with largely decreased probability of survival to CCN size at the summit of Mt. Tai under reduced SO2 emissions

Zhu¹,

Xue²,

Gao³

et al. 2020

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Abstract. Because anthropogenic sulfur dioxide (SO2) emissions have decreased considerably in the last decade, PM2.5 pollution in China has been alleviated to some extent. However, the effects of reduced SO2 on the particle number concentrations and subsequent contributions of grown new particles to the cloud condensation nuclei (CCN) populations, particularly at high altitude with low aerosol number loadings, are poorly understood. In this study, we evaluated the campaign-based measurements made at the summit of Mt. Tai (1534&#8201;m&#8201;a.s.l.) from 2007 to 2018. With the decrease in the SO2 mixing ratios from 15&#8201;&#177;&#8201;13&#8201;ppb in 2007 to 1.6&#8201;&#177;&#8201;1.6&#8201;ppb in 2018, the formation rate of new particles (FR) and the net maximum increase in the nucleation-mode particle number concentration (NMINP) increased by 2&#8211;3 fold in 2018 against those in 2007. In contrast, the occurrence frequency of new particle formation (NPF) events in which the maximum geometric median diameter of grown new particles (Dpgmax) was >&#8201;50&#8201;nm decreased considerably from 43&#8201;%&#8211;78&#8201;% of the NPF events before 2015 to <&#8201;12&#8201;% in 2017&#8211;2018. Assuming >&#8201;50&#8201;nm as a CCN threshold size at high supersaturations, the observed net CCN production decreased from 3703&#8201;cm&#8722;3 (on average) before 2015 to 1026&#8201;cm&#8722;3 (on average) in 2017&#8211;2018. We argue that the increase in the FR and NMINP is mainly determined by the availability of organic precursors that participate in nucleation and initial growth, whereas the decrease in the growth probability is caused by the reduced emissions of anthropogenic precursors. However, large uncertainties still exist because of a lack of data on the chemical composition of these smaller particles.

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An approach to investigate new particle formation in the vertical direction on the basis of high time-resolution measurements at ground level and sea level

Cited by 16 publications

References 34 publications

New particle formation in marine atmosphere during seven cruise campaigns

New particle formation in marine atmosphere during seven cruise campaigns

Large increases in N<sub>cn</sub> and N<sub>ccn</sub> together with a nucleation-modeparticle pool over the northwestern Pacific Ocean in the spring of 2014

Increased new particle yields with largely decreased probability of survival to CCN size at the summit of Mt. Tai under reduced SO<sub>2</sub> emissions

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An approach to investigate new particle formation in the vertical direction on the basis of high time-resolution measurements at ground level and sea level

Cited by 16 publications

References 34 publications

New particle formation in marine atmosphere during seven cruise campaigns

New particle formation in marine atmosphere during seven cruise campaigns

Large increases in N&lt;sub&gt;cn&lt;/sub&gt; and N&lt;sub&gt;ccn&lt;/sub&gt; together with a nucleation-modeparticle pool over the northwestern Pacific Ocean in the spring of 2014

Increased new particle yields with largely decreased probability of survival to CCN size at the summit of Mt. Tai under reduced SO&lt;sub&gt;2&lt;/sub&gt; emissions

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Large increases in N<sub>cn</sub> and N<sub>ccn</sub> together with a nucleation-modeparticle pool over the northwestern Pacific Ocean in the spring of 2014

Increased new particle yields with largely decreased probability of survival to CCN size at the summit of Mt. Tai under reduced SO<sub>2</sub> emissions